Kinetics of highly excited states in Ar¹⁷⁺charge exchange recombination fusion plasma spectroscopy

Abstract

Charge exchange (CX) between impurities and injected neutral particles, which results in line emission from highly excited states of impurity ions, is the basis of an important technique for spectroscopic diagnostics of fusion plasmas. In this paper, we study the temporal kinetics of highly excited nl states (n ⩽ 20) of H-like argon under typical conditions of a CX recombination experiment in tokamaks. A two-zone model is implemented to describe the tokamak plasma with and without a neutral beam. A detailed time-dependent collisional- radiative model describing ions of Ar15+ through Ar18+ and the atomic processes that affect the excited levels is used to determine the level densities. The relative contributions of atomic processes to population influx and outflux with and without CX are discussed in detail. The simulations show that after injection of a neutral beam, the populations of excited states oscillate between two quasi steady-state conditions, and the relaxation of ionization equilibrium is reached on times much longer than a typical plasma rotation time in a tokamak.

Calculations and analysis of cross sections required for argon charge exchange recombination spectroscopy

“…Advances in the study of fusion plasmas rest on both improvements in plasma modelling and in measurements, and these often depend in turn on the availability of reliable and comprehensive atomic data. A prominent instance of this is charge exchange recombination spectroscopy (CXRS) [1][2][3][4], an important plasma diagnostic technique that requires extensive knowledge of the charge transfer process involving neutrals such as hydrogen and highly charged ions.…”

Collisional excitation and emission ofHαStark multiplet in fusion plasmas

“…This code has been extensively used for spectroscopic diagnostics of laboratory, fusion and astrophysical plasmas. An example of NOMAD application to neutral beams in tokamaks can be provided by the recent study on the kinetics of highly excited states of impurities that are used in charge-exchange recombination spectroscopy experiments [19]. The number of hydrogen states considered in the present work was restricted to n 5 due to two reasons.…”

Medical Ultrasound Imaging Using Pulse Compression Technique Based on Split and Merge Strategy

“…We also plan to investigate whether charge exchange is an important process in the spectroscopy of fusion plasmas. In particular, it has recently been shown that the population kinetics of highly excited states [22] can be strongly affected by charge exchange between plasma impurities and injected neutral particles. We hope to incorporate charge-exchange processes in our modelling capabilities in the near future.…”